This application relates to truly breakerless electronic self-powered ignition systems. No physical switches whatsoever are used in these systems. They are entirely solid-state with the associated solid-state reliability.
There are a number of electronic ignition systems available for internal combustion engines in which the breaker points have been eliminated by use of electronic switches. Still further, mechanical distributors in which a rotating electrode or brush establishes physical contact with poles associated with each spark plug have been replaced with magnetically activated switches such as reed switches and mercury switches. These are not, however, truly breakerless distributors as mechanical action (caused by moving a magnetic pole near the switch) is still involved. This invention relates to a truly breakerless or solid-state ignition and distribution system.
This application is particularly directed to self-powered ignition systems; that is, those having no auxiliary electric power source (such as a battery) available at start-up. These ignition systems are powered by DC current generators, alternators, and magnetos.
While, for the most part, this application is directed to ignition systems, i.e., means for creating a spark in a cylinder of an internal combustion engine at the appropriate instance in the engine cycle, it is also directed to fuel injection systems in which fuel is injected into cylinders near the end of the compression stroke. Since electrical pulses are used to activate fuel injection solenoids in fuel ignition systems, this invention is useful in both spark ignitions and fuel injection systems.
Breakerless distributors require electronic sensing devices. These sensing devices, in cooperation with a rotating element, perform the indexing function previously performed by the rotating brush and poles of prior art distributors. A number of electronic sensing devices are available. However, they have not found use with ignition systems and especially with self-powered ignition systems due to the supply current requirement. Magnetically operated Hall effect switches and LED triggered photosensitive electronic switches are two such electronic sensing and switching devices. The supply current requirements for the sensor element (for example, the Hall element in the Hall effect switch and the LED of the LED trigger switch) can equal or exceed the operating current requirement of the ignition circuit itself. For example, in the case of a Hall element a supply current of 4 to 10 milliamps is required and if low tension electronic distribution is required one Hall element per cylinder is also required. Connected in parallel then, a 10 cylinder system would require 40 to 100 milliamps of supply current. The LED (light emitting diode) supply current can be 20 to 100 milliamps. Now then, a typical supply current for an entire ignition system may only be 40 to 100 milliamps. While it is conceivable that the supply current for the sensing elements could be supplied at the normal running speed of the engine, at cranking or starting speeds (rpm) the generator output is far too low (a few milliamps at best). Hence, electronic sensing devices with an associated current drain have not been used in ignition systems and the like.
Briefly, according to this invention there is provided a breakerless pulse generating and distributing system comprising an energy storage means such as a storage capacitor and means for charging the energy storage means. A plurality of electronic power switches in parallel are each arranged to discharge the energy storage means. A pulse generator is arranged to generate a timing pulse at given angular positions of a rotating member. A distributor comprises a plurality of electronic sensor-switches for passing the timing pulse to the control terminal of the power switches. Each sensor-switch has a power supply terminal and an associated current drain. The power supply terminals of the sensor-switches are connected to the pulse generator. The sensor-switches are individually activated by a breakerless means associated with a rotating member at given angular positions thereof. In this way, each sensor-switch is arranged to pass the timing pulse to the control terminal of a corresponding electronic power switch when the breakerless means is indexed with a sensor-switch. The sensor-switch thereby drains current only during the timing pulses.